Piston skirt expander



Aug. 26, 1941. FALL 2,254,030

PISTON SKIRT EXPANDER Filed Aug. 5. 1940 Patented Aug. 26, 1941 UNITED STATES PATENT OFFICE PISTON Appllcaflsl i zl l l lfzf i:TifiZifio. 350,228

15 Claims.

, in which the side thrust is applied to the piston.

Piston expanders have been known and used successfully for some time, but most of those now known and in use possess certain faults which detract from their utility.

One of the prinicipal objects of the present invention is to provide a piston skirt expander which is arranged to bear against the inner surface of the piston skirt over a considerable area so that the pressure which must be applied by the expander if it is to be eflective will be distributed and will not be excessive at any one point.

Another object of the present invention is to provide a piston expander which is located in the piston by at least three lugs, and preferably four, so that there will be no possibility of the expander becoming tipped in the piston when the piston is in operation.

Still another object of this invention is to provide a piston skirt expander which can be readily compressed and held in its compressed position while it is being placed in the piston, thus facilitating the installation of the expander.

One of the principal features of this invention is the provision of a piston skirt expander in the form of a string inverted U-shape spring adapted to fit within a piston and the provision of pressure pads on each end of the spring for applying the pressure from the spring over a substantial area of the piston skirt. Another feature of the invention is the provision of two lugs on each of the pressure pads, the lugs being adapted to flt into holes drilled in the piston skirt and serving to positively prevent cooking or tipping of the expander.

Other objects and features of the invention will appear from the following description and the appended claims, taken in connection with the accompanying drawing, in which:

Figure 1 is a central vertical section through a piston having installed therein an expander forming one of the preferred forms of the invention, this figure also showing a tool used for installing the expander;

Figure 2 is a view looking up at the bottom of the piston and expander shown in Figure 1, the tool being omitted;

Figure 3 is a side elevation of the expander by itself before it is contracted for insertion into the piston:

Fi ure 4 is a plan view of the expander installed in a piston, portions of the piston skirt being shown in section to illustrate how the expander flts against them: and

Figure'5 is a view of one leg of the expander fitting against the inside of the piston skirt, the view being a section taken on the line V--V of Figure 4 and looking in the direction of the arrows.

Figure 6 is a fragmentary detail sectional view showing one method of attaching the pressure pad.

The particular form of the invention shown in the drawing comprises an inverted U-shape piece of heavy spring wire I0 having a pressure pad H welded or otherwise secured at each end. Each pressure pad II is made of a single piece of sheet metal and comprises a back or main portion l2 lying in contact with the outside of the spring wire or rod I0 near its end, and curved, as shown in Figures 2 and 4, to fit the inside of the piston skirt. The back I2 of the pressure pad II is reinforced by two flanges l3 and I4 along its upper and lower edges, the top flange l3 having a hole through which the end of the spring rod H! extends and the bottom flange l4 passing immediately under and in contact with .end of the spring rod Ill. The pressure pad II is also provided with two lugs I 5, which are formed integrally with and extend radially out from the end of the back or main portion l2 of the pressure pad.

Either the upper or the lower flange l3 or I may be extended in beyond the spring rod iii and formed with an aperture or other means for connecting an inserting toool to the ends of the expander. In the particular form of the invention shown in the drawing, the upper flange l3 of the pressure pad is extended in and is provided with an aperture it into which one end ll of an inserting tool I 8 may be engaged. The other end I! of the inserting tool is engaged in the corresponding aperture I6 at the other end of the expander, permitting the inserting tool l8 to be operated to draw the ends or legs of the expander close enough together to allow the expander to be inserted within the skirt l9 of a piston 20, as shown-in Figure 1.

Before the expander is inserted in the piston, the skirt I9 is drilled with four holes 2| located in the proper positions to receive the lugs 15 when the expander is placed within the piston on a plane perpendicular to the axis of the piston pin. as shown in Figures 1 and 2. A template may be provided for conveniently and accurately locating the holes 2| in the proper position with respect to each other and at the proper distance above the lower .edge of the skirt is. The size of the holes 2| is such that the lugs l5 flt into them tightly, and the two lugs l5 fitting into the two holes 2| at each side positively and securely hold the expander against tipping or rocking while in service.

In Figure 6 I have shown a method of attaching the pressure pad which eliminates the necessity of welding. In this method the ends of the spring rod III are flattened as at N and the portion I! of the pressure pad is made of sufficient length so that it may be crimped over and around said flattened ends as at H to secure the pad against relative rotation and in association with the rod. Y

From the above, it will be obvious to those skilled in the art of rebuilding or repairing engines that I have provided an extremely simple and effective piston skirt expander that can be used even with pistons having very thin skirts without there being any danger of breaking these skirts. I This danger is avoided by the use of the accurately formed and stiff pressure pads II which distribute the pressure ,of the expander over a substantial area of the skirt.

While I have shown and described only one of the preferred forms of my invention, it will, of course, be understood that other forms of the invention may be constructed. My invention, therefore, not only includes the particular form which I have shown and described but any modifications thereof which may occur to the skilled mechanic and fall within the terms of the appended claims.

I claim:

1. In a piston skirt expander comprising a U- shaped piece of spring rod, sheet metal pressure pads secured at the ends of said rod, the outer surface of each of said pressure pads being curved in concentric relation to and for seating against the inside of said piston skirt.

2. In a piston skirt expander comprising a U- shaped piece of spring rod, pressure pads secured at the ends of said rod, the outer surface of each of said pressure pads being convex and concentric to the concave cylindrical interior surface of said skirt for seating engagement thereagainst.

3. In a piston skirt expander comprising a U- shaped piece of spring rod, sheet metal pressure pads secured at the ends of said rods, each of said pads comprising a main portion flxed to the side of said rod and flanges at the top and bottom of said main portion, said flanges extending substantially perpendicularly to said rod.

4. In a piston skirt expander comprising a U- shaped piece of spring rod, sheet metal pressure pads secured at the ends of said rods, each of said pads comprising a main portion fixed to the side of said rod and flanges at the top and bottom of said main portion, said main portion being curved to fit against a substantial area on the inside of said piston skirt and said flanges extending substantially perpendicularly to said rod.

5. In a piston skirt expander comprising a U- shaped piece of spring rod, sheet metal pressure pads secured at the ends of said rod, each of said pads comprising a main portion fixed to the side of said rod, and flanges at the top and bottom of said main portion, said flanges extending substantially perpendicularly to said rod and one of said flanges having an aperture therein for receiving a tool for contracting said expander.

6. In a piston skirt expander comprising a U- shaped piece of spring rod, sheet metal pressure Iv inside of a piston, a pair of spaced lugs fixedly,

secured on at least one end of said rod lying in a single plane angularly disposed from the plane of said U-shaped rod and adapted to flt into spaced holes in said piston skirt.

8. In a piston skirt expander comprising a U- shaped piece of spring rod substantially diametrically bridging in a single plane the sides on the inside of a piston, pressure pads extending transversely of the plane and On both sides of said rod and flxed on the ends of said rod to prevent movement relative to the rod, and lugs projecting from each end of each of said pressure pads, said lugs being adapted to fit into spaced holes in said piston skirt to prevent tilting of said expander from said bridging plane in said skirt.

9. A piston skirt expander comprising a U- shaped piece of spring rod having flattened ends, sheet metal pressure pads secured at the ends of said rod, each of said pads comprising a main portion afllxed to the side of the rod and flanges at the top and bottom of said main portion, said flanges extending substantially perpendicular to said rod and said rod passing through the flange at the top of said pressure pads and the flattened portions of said rod being engaged by crimped portions of the flange at the bottom of said pres sure pads.

10. In a piston skirt expander, an element comprising a U-shaped rod of spring material having a surface on each end thereof, with the surfaces in parallel relation and facing each other, said ends each coacting with an embracing piston seating element to form a flxed connection therebetween.

11. In a piston skirt expander, the combination with expanding means of a pressure pad comprising a strip of material havinga longitudinally curved web, and spaced flanges extending toward the center of curvature of said web from the side edges thereof.

12. In a piston skirt expander, the combination with expanding means of a pressure pad comprising a strip of material having a longitudinally curved web, means at the ends of said web for securing said web to a piston, and spaced parallel flanges of unequal length extending toward the center of curvature of said web from the side edges thereof.

13. In a piston skirt expander, a pressurepad comprising a strip of material having a longitudinally curved web, positioning lugs at the ends of said web for securing said pad to a piston, spaced parallel flanges of unequal length extending toward the center of curvature of said web from the side edges thereof, and apertures in said flanges for receiving pressure inducing means.

14. In a piston skirt expander, a pressure pad comprising a strip of material having a longitudinally curved web, spaced parallel flanges of unequal length extending toward the center of curvature of said web from the side edges thereof, spaced apertures in the longer of said unequal flanges, and an upturned flange at the free end of the shorter 01' said unequal flanges.

15. In a piston skirt expander, a U-shaped spring element, piston engaging pressure pads at the ends of said element, means connecting said element and pads to prevent relative movement therebetween, and spaced means on said pads cooperating with the engaged portions of a piston for movably maintaining said spring element in one plane relative to the engaged piston.

ALBERT P. FALL. 

